Could cancer screening be harmful?

30 October 2011

Dollar-wise, how much is a life worth? How much are we as a society willing to pay to “save” a life? Even so, are we more willing to save a life of a child than a senior citizen? A vegetable than a genius? These are examples of open-ended questions that might not ever have perfect answers, but through discussion and rational debate it might be possible to arrive at better answers.

Cancer epidemiologists have postulated for 70 years that cancer caught early could be curable by surgery (Mukherjee 2010). “Early” being defined as before the primary tumor had begun to metastasize and spread to distant organs. But even that view is not without nuances, as it is becoming more apparent that some cancers will begin to metastasize early, and some will never metastasize at all. This week Gina Kolata of the New York Times penned a curious article on how some cancer screening can be harmful.

In short, it is becoming clearer that, in the case of breast and prostate cancer, those readily caught early are also the ones that are usually slow-growing and not life-threatening. As a result, cancer screening might actually result in more surgical and chemotherapeutic interventions than necessary. Or, our current screening techniques might be unable to catch the dangerous cases of cancer.

However, no medical knowledge is inherently harmful. It is the subsequent actions (and perhaps non-actions) that can cause harm to patients. It may be that our knowledge of which cancers will begin to spread quickly and those that do not isn’t up to par. Even within breast cancer there are several distinct subclasses of the disease defined by particular molecular signatures that trigger different disease progression.

Thus, not all “breast cancer” is the same disease. Some types might metastasize and spread earlier in disease progression. Some might remain benign and not life-threatening. Better characterization of such will allow not only for early detection, but better plans of action for treatment, or non-treatment.